Confection of mechanical analog model for the study of Brownian motion and molecular diffusion

In this article we describe the setup of a mechanical system that simulate the stochastic propagation process of a brownian particle inside a fluid. Our system consist of a mechanical oscillator coupled to a recipient which is shacked constantly. Inside the recipient we deposit small “fluid particles” that remain in constant agitation. Inside this “fluid” we insert one bigger test Brownian particle (bigger than the fluid particles) over which the small fluid particles exert random stochastic forces. We analyze the zigzag movement of the Brownian particles by filming the motion and using the free software Tracker in order to realize the image analysis. Our results show an excellent qualitative agreement between the predictions of the brownian motion theory and our experimental results. The advantage of introducing in this way the concepts of brownian motion and molecular diffusion is that we can observe by the naked eye this phenomenon happening.

Keywords
Brownian motion; mechanical analog model; stochastic processes